This application claims benefit of priority under 35 U.S.C. xc2xa7 119 to Japanese Patent Application No. 2000-145453, filed on May 17, 2000, the entire contents of which is incorporated by reference herein.
1. Field of the Invention
This invention relates to a semiconductor device, a method of manufacturing a semiconductor device, a resin molding die, and a semiconductor manufacturing system, and more particularly relates to a semiconductor device in which at least one semiconductor element (e.g. a semiconductor chip) is encapsulated in a resin seal, a method of manufacturing such a semiconductor device, a resin molding die used in the methods, and a semiconductor manufacturing system for carrying out the foregoing semiconductor device manufacturing method.
2. Description of Related Art
Semiconductor devices having the ball grid array structure are well-known at present. Referring to FIG. 25 and FIG. 26 of the accompanying drawings, such a semiconductor device comprises: a substrate 1 made of a resin, a tape, ceramics or the like and having a wiring circuit formed thereon; a semiconductor chip 2 fixedly mounted on the substrate 1 using an adhesive layer 3; a bonding wire 5, e.g. a gold bonding wire, connecting a bonding pad of the semiconductor chip 2 and a wiring circuit terminal 4 on the substrate 1; and a resin seal 6 for encapsulating the semiconductor chip 2. A resin gate scar 6G via which resin was injected for the transfer molding process remains on a side surface of the resin seal 6. External connection terminals 8 constituted by solder balls are electrically connected to the wiring circuit terminal 4 on the rear surface of the substrate 1.
FIG. 27 and FIG. 28 show a cavity-down type semiconductor device having the ball grid array structure. The semiconductor device comprises: a substrate 1 made of a resin, a tape, ceramics or the like and having a wiring circuit and a through-hole on the center thereof; a metal plate 10 or an insulated plate 10 stuck onto the substrate 1 by an adhesive layer 9; a semiconductor chip 2 fixedly attached by an adhesive layer 3 in a recess defined by the through-hole in the substrate 1 and the plate 10; a bonding wire 5, e.g. a gold bonding wire, connecting a bonding pad of the semiconductor chip 2 to a wiring circuit terminal 4 on the rear surface of the substrate 1; and a resin seal 6 encapsulating the semiconductor chip 2. A resin gate scar 6G via which resin was injected for the transfer molding process remains on a side surface of the resin seal 6. External connection terminals 8 constituted by solder balls are electrically connected to the wiring circuit terminal 4 on the rear surface of the substrate 1, i.e. where the wiring circuit terminal 4 is provided.
The semiconductor device of FIG. 25 and FIG. 26 is resin molded as shown in FIG. 29A and FIG. 29B. A resin molding die including upper and lower dies 11 and 12 is heated to a temperature of approximately 165xc2x0 C. to 185xc2x0 C. Thereafter, a resin tablet or powder 14 is supplied to a pot 13 in the lower die 12. The substrate 1, on which the semiconductor chip 2 and the bonding pad of the semiconductor chip 2 are provided and is connected to the wiring circuit terminal 4 using the gold bonding wire 5, is placed between the upper and lower dies 11 and 12. In this state, the upper and lower dies 11 and 12 are clamped as shown in FIG. 29A. The resin 14 in the pot 13 is pressurized using a plunger 15 and melted, and is injected into a cavity 17 via a runner 16 and the resin gate 7. The resin 14 is left as it is for approximately 40 seconds to 180 seconds, and is hardened in order to form the resin seal 6. Thereafter, the upper and lower dies 11 and 12 are unclamped, so that the resin seal 6 is removed from the upper and lower dies 11 and 12. By this, the semiconductor device is almost completed. The resin seal 6 includes superfluous resins 14A such as a cull 18, runner 17 and resin gate 7 formed when injecting the resin 14, which are removed by the gate-breaking, and are discharged.
In order to facilitate the peeling of the unnecessary resin 14A in the gate-breaking, a metal part 19 is sometimes provided over the runner 16 and resin gate 7 on the substrate 1, as shown in FIG. 30.
In the semiconductor device of FIG. 27 and FIG. 28, the resin seal 6 is at the center of the rear surface of the substrate 1, and is surrounded by the external connection terminals 8. Therefore, if the runner 16 extends over a part of the external connection terminals 8 (solder balls), a part of the surplus resin 14A may stick on them. Some surplus resin 14A may scrape a part of external connection terminals 8 which are being formed. Any of resin molding processes shown in FIG. 31 to FIG. 34 is utilized in order to overcome this problem.
In a first resin molding process shown in FIG. 31, a resin is injected with a third die or a plate 20 inserted between upper and lower dies 11 and 12. Specifically, the third die or plate 20 extends all over the external connection terminals 8 on the rear surface of the substrate 1, so that the resin cannot stick onto the external connection terminals 8.
According to a second resin molding process shown in FIG. 32, the resin is injected with a sheet 21 such as a film sandwiched between the upper and lower dies 11 and 12. Similarly to the third die or plate 20, the sheet 21 extends all over the external connection terminals 8 on the rear surface of the substrate 1, which can prevent the resin from sticking onto the external connection terminals 8.
A third resin molding process shown in FIG. 33 is described in Japanese Patent Laid-Open Publication No. Hei 7-221132, for example. In this method, a resin inlet 22 is in the shape of a recess and extends between the pot 13 in the lower die 12 and the plate 10 connecting to the pot 13. Further, a resin outlet 23 extends to the cavity 17 from the resin inlet 22. The resin 14 in the pot 13 is pushed upward using a plunger 15 in order to fill the cavity 17 via the resin inlet 22 and the resin outlet 23. Both the resin inlet 22 and the resin outlet 23 are formed in the substrate 1. Since no resin 14 passes over the external connection terminals 8, it is possible to prevent the resin 14 from sticking onto the external connection terminals 8.
A fourth resin molding process is similar to the third method. However, the fourth method is applied to a cavity-up type semiconductor device as shown in FIG. 34. This semiconductor device comprises: a substrate 1 made of a resin, a tape, ceramics or the like and having a wiring circuit provided thereon; a frame 24 made of a metal plate or an insulated plate, having a through-hole at the center thereof and stuck onto the front surface of the substrate 1 using an adhesive layer 25; a semiconductor chip 2 fixedly attached using an adhesive layer 3 in a recess defined by the substrate 1 and the through-hole in the frame 24; a bonding wire 5, e.g. a gold bonding wire, connecting a bonding pad of the semiconductor chip 2 to a wiring circuit terminal 4 on the front surface of the substrate 1; and a resin seal (not shown) encapsulating the semiconductor chip 2. In this method, a resin inlet 22 in the shape of a recess is formed in the frame 24 and around the semiconductor chip 2 and is connected to the pot 13 provided in the lower die 12. Further, a resin outlet 23 extends from the resin inlet 22 to the cavity 17. The resin 14 in the pot 13 is pushed upward by the plunger 15, and injected into the cavity 17 via the resin inlet 22 and the resin outlet 23. Both the resin inlet 22 and the resin outlet 23 are formed in the substrate 1, so that no resin 14 passes over the external connection terminals 8. This is effective in preventing the resin 14 from sticking onto the external connection terminals 8.
However, the foregoing semiconductor device and the foregoing manufacturing methods seem to suffer from the following problems.
(1) In the resin molding process shown in FIG. 29A and FIG. 29B for the semiconductor device of FIG. 25 and FIG. 26, there are formed not only the resin seal 6 but also the unnecessary resin 14A such as the cull 18 of the molding die, runner 16 and resin gate 17. The unnecessary resin 14A is removed from the rein seal 6 after the gate-breaking, and is discharged as waste. As a result, most of the resin 14 housed in the pot 13 would be wasted, which not only increases the manufacturing cost of the semiconductor devices but also is not desirable in view of effective use of resources.
(2) During the gate-breaking, the resin seal 6 may peel off from the substrate 1, or may crack, which would adversely affect the reliability of the semiconductor device and reduce the manufacturing yield of the semiconductor device.
(3) In the semiconductor device shown in FIG. 30, no wiring circuit for the wiring circuit terminals 4, external connection terminals 8 and so on can be arranged in the area where the metal part 19 is provided in order to facilitate the gate-breaking, so that the substrate 1 becomes large due to the metal part 19, which makes it difficult to downsize the semiconductor device.
(4) With the resin molding process shown in FIG. 29A and FIG. 29B, if the substrate 1 whose thickness is larger than the predetermined value because of dispersion of manufacturing quality is placed in the molding die, there may be a gap between the upper and lower dies 11 and 12 near the pot 13 and the runner 16. Conversely, if the substrate 1 is thinner than the predetermined value, a gap is caused between the upper die 11 and the substrate 1. If the substrate 1 is too thick, the resin 14 tends to leak via the gap when it is being injected. Especially, a substrate 1 made of sintered ceramics and having a reduced dimensional tolerance has low elasticity and is slow to be deformed during the die clamping. This means that the resin frequently leaks if the substrate 1 has a thickness deviating from the predetermined value. Further, the thicker the ceramics substrate, the more easily it cracks.
(5) The first resin molding process shown in FIG. 31 for the semiconductor device of FIG. 27 and FIG. 28 requires the provision of the additional die or plate 20 between the upper and lower dies 11 and 12. Further, the second resin molding process of FIG. 32 needs the sheet 21 to be provided. It is extremely difficult to automatically attach the additional die or plate 20, or the sheet 21 to a general purpose transfer molding system. For this purpose, a new dedicated device has to be provided. In addition, the additional die or plate 20, or the sheet 21 has to be prepared, which would adversely increase the manufacturing cost and product cost of the semiconductor device.
(6) In the third and fourth resin molding processes shown in FIG. 33 and FIG. 34, both the substrate 1 and the frame 24 are thickened in order to form the resin inlet 22 and the resin outlet 23. Further, no external connection terminals 8 can be provided on the area for the resin inlet 22, so that not only the substrate 1 but also the frame 24 have to become large. Therefore, it is very difficult to downsize the semiconductor device. Still further, since the resin inlet 22 and the resin outlet 23 are provided in the substrate 1 or the frame 24, the mechanical strength of the substrate 1 where the rein inlet 22 and the resin outlet 23 are positioned is reduced, which requires the substrate 1 or the frame 24 to be enlarged in order to secure sufficient mechanical strength. In short, it is extremely difficult to downsize the semiconductor device. In addition, the resin inlet 22 and the resin outlet 23 should be machined by special processes, which adversely increases the manufacturing cost and product cost of the semiconductor device, and reduces the manufacturing yield of the semiconductor device.
This invention has been devised in order to overcome the foregoing problems of the related art. A first object of the embodiment of the invention is to provide a method of manufacturing a semiconductor device which is free from resin waste generated during the formation of a resin seal, and is less expensive.
A second object of the embodiment of the invention is to provide a method of manufacturing a reliable semiconductor device which is protected against the peeling of a resin seal and shorting of wires, and improves manufacturing yield.
It is a third object of the embodiment of the invention to provide a resin molding die which is effective in carrying out the foregoing semiconductor device manufacturing method.
A fourth object of the embodiment of the invention is to provide a semiconductor manufacturing system to which the foregoing semiconductor device manufacturing method is applicable.
A final object of the embodiment of the invention is to provide a reliable semiconductor device.
According to a first aspect of the invention, there is provided a method of manufacturing a semiconductor device comprising: (1) arranging at least one semiconductor element in a cavity of a resin molding die; (2) supplying a resin to a resin reservoir in direct contact with the cavity in order to substantially fill the cavity; and (3) injecting the resin into the cavity from the resin reservoir in order to form a resin seal for encapsulating the semiconductor element.
In accordance with a second aspect of the invention, there is provided a method of manufacturing a semiconductor device comprising: (1) arranging at least a base and a semiconductor element on the base in a cavity of a resin molding die; (2) supplying a resin to a resin reservoir in direct contact with the cavity and above the semiconductor element in order to substantially fill the cavity; and (3) injecting the resin into the cavity from the resin reservoir in order to form a resin seal for encapsulating at least a part of the base and the semiconductor element.
With a third aspect of the invention, there is provided a method of manufacturing a semiconductor device comprising: (1) arranging at least a base and a semiconductor element on the base in a cavity of a resin molding die; (2) supplying a resin to a resin reservoir at the center of the cavity facing with an upper surface of the semiconductor element in order to substantially fill the cavity; and (3) injecting the resin into the cavity from the resin reservoir in order to form a resin seal for encapsulating at least a part of the base and the semiconductor element.
According to a fourth aspect of the invention, there is provided a resin molding die comprising: a cavity; a resin reservoir in direct contact with the cavity and housing a resin for substantially filling the cavity; and a pusher injecting the resin into the cavity from the resin reservoir.
In accordance with a fifth aspect of the invention, there is provided a semiconductor manufacturing system comprising: a resin molding die which includes a cavity, a resin reservoir in direct contact with the cavity and housing a resin for substantially filling the cavity, and a pusher injecting the resin into the cavity from the resin reservoir; a plunger for driving the pusher of the resin molding die; a plunger driving unit for driving the plunger; and a control unit for driving the plunger driving unit.